Meanwhile, “codes” as referred to in the present application includes a code printed on a label, an exterior surface of a case and so forth, especially a bar-code and a code in a magnetic stripe of a magnetic card.
With respect to a reader for codes, for example, a conventional bar-code reader for bar-codes printed on labels and so forth, there are cases where decode fails because of unevenness of printing of a bar-code and so forth.
Against this problem, PTL 1 discloses a bar-code reading device and a bar-code reading method comprising a counting means for counting the number of data of a light reception signal belonging to each section of a plurality of sections obtained by dividing an amplitude of the light reception signal at a light reception element by predetermined intervals, an integration means for successively integrating the number of data belonging to the sections which are equal to or larger than, in number, a plurality of predetermined amplitudes to set a count value based on the number counted by the counting means of data, and a determination means for determining whether or not any section in which the count value integrated by the integrating means is larger than a predetermined value exists in said sections which are equal to or larger than, in number, the plurality of predetermined amplitudes, and thereby determining that there is not an effective reception signal within a range of large amplitude by an assumed value although there is an extremely large amplitude by regular reflection and so forth and being able to read exactly bar-codes without being effected by background environment such as regular reflection.
Further, PTL 2 discloses a signal processing device comprising a circuit arrangement with an automatic gain control system into which a gain adjustment element as controlled on the basis of an output from a luminescence element is built and thereby performing adequate gain control and solving restriction of resolution of bar-codes and a readable range by effect to reflection light quantity on the basis of a difference between a bar-code reading device to a bar-code.